The invention relates to a mechanism for the adjustment, the locking and the releasing of the adjustable engagement jaws of a mobile telephone or PDA holder.
Such a mechanism is known from German patent DE 195 42 720. This patent discloses a mobile telephone/PDA holder with a base body on which the mobile telephone, the PDA or a similar apparatus such as a mobile navigation apparatus can be placed and firmly engaged by two clamping jaws which are movable in synchronism toward, and away from, one another by a mechanism disposed in the base body. The mechanism provides for the synchronous opening and closing of the jaws and the automatic locking of the jaws in their closed positions.
In the known holder, the two engagement jaws are interconnected for the synchronous movement by a coupling mechanism which includes a rotatably supported control disc with diametrically opposite elongated radial openings. In each opening, a pin is received which projects from a guide leg of one or, respectively, the other of the engagement jaws providing for the synchronous movement of the engagement jaws as they are coupled by the control disc in whose elongated openings the pins of the engagement jaw legs are received.
A displacement of the jaws toward, or away from, each other therefore always occurs synchronously and uniformly, because the two clamping jaws are coupled with each other by way of the pins and the wheel receiving the pins in its radial elongated openings. A compression spring arrangement between the base body and the jaws biases the jaws into their opening positions.
The known mechanism further includes a gear which is rotatably connected to the wheel of the coupling mechanism which is engaged by a locking claw. The locking claw is provided on a slide member whose free end is a release key. The locking claw projects from the base body and is biased into engagement with the gear. The locking claw therefore forms with the gear a ratchet mechanism. By actuation of the release key, the locking claw is removed from the gear so that the two clamping jaws are moved synchronously apart from each other to their outermost opening positions. After the insertion of the apparatus into the holder the jaws are manually moved together whereby the gear slides over the engagement claws which are biased to its engagement position because the teeth of the gear are so shaped that they make such a ratchet movement possible upon closing of the clamping jaws but prevent movement of the gear in the opening direction of the jaws. The clamping gears are therefore only released when the release key is pressed in and, as a result, the locking claw is moved out of its engagement position with the gear.
Since the teeth of the known apparatus must have a certain width in the circumferential direction of the gear the jaws are closed in a stepwise fashion in that the closing of the clamping jaws progresses with the ratcheting of each tooth of the gear over the ratchet claw. Accordingly, the subsequent locking position of the clamping jaws which are increasingly closer are spaced by a certain distance from one another without the possibility of setting any intermediate positions. Since, consequently, the distance between the clamping jaws can be changed only in steps the clamping jaws must be provided at their engagement surfaces with a relatively thick resilient backing in order to provide for secure engagement of an apparatus disposed between the clamping jaws. In addition, during the closing of the known mechanism, an undesirable ratcheting noise is generated.
U.S. Pat. No. 5,788,202 additionally discloses another mechanism which, in place of a gear, uses a friction wheel which, at its circumference, is provided with a rubber layer and includes two oppositely arranged friction wedges which cooperate to frictionally engage the friction wheel therebetween. However, it has been found in practice that this arrangement is subject to certain problems which render the arrangement ineffective under certain circumstances: At large temperature changes as they occur with the use of the holder in vehicles, it has been found that the clamping jaws were sometimes released when the vehicle was exposed to the sun so that they were moved by the springs to their open end positions so that the apparatus was not reliably held in its engaged position.
It is the object of the present invention to improve the mechanism of mobile telephone or PDA holders with adjustable clamping jaws in such a way that the closing movement of the clamping jaws and the locking of the clamping jaws in the respective engagement positions is achieved without noise and also in a stepless and reliable fashion.